Effects of Surface and Sub-Surface Irrigation

In sprinkler irrigation techniques, water distribution occurs from a central location by a high-pressure sprinkler or gun, called the solid-set irrigation system. These sprinklers behave like a rotor and operate at extremely high pressure. As a result, the flow of water is also usually high. Often, they possess a nozzle and remain mounted on a rotating platform. A hose usually connects these sprinklers to the water source.

Drip irrigation is the most effective and commonly used technique. It is a low-pressure system that helps irrigate sloping lands. This technique results in uniform application of the water throughout the agricultural field and ensures consistent crop yields. It transports water to the root zone of every crop in the field. This method utilizes pipes called dripper lines that run across agricultural fields. They consist of smaller units called drippers, which are holes. Water and nutrients drip from the holes into the root of the crops. As the water slowly drips, the loss of water by evaporation decreases. Drip irrigation prevents wastage of water. This method mediates uniform application of nutrients by injecting and mixing water-soluble fertilizers in the irrigation system.

Surface and Sub-Surface Irrigation
Surface irrigation utilizes gravity to distribute water over the entire field surface. This method uses a source of water that is at an elevated point compared to the field. Surface irrigation does not require channels or pipelines to transport water. Instead, soil acts as the medium for water transportation.

The two basic categories that comprise surface irrigation are moving water and ponding. The moving water method may require adequate runoff so that the proper infiltration of water occurs. Ponding is beneficial when evaporation levels are the lowest, that is, early morning or night. Several factors determine how efficient surface irrigation will be. These factors include the soil quality, elevation, field level, runoff, and the size of the water source. A small investment is enough to set up this irrigation system in preliminary fields, and it requires no additional energy requirements. However, it is labor-intensive. The application of water may not be uniform. In addition, this method is less efficient than other irrigation methods as it leads to water loss by evaporation.

The sub-surface irrigation method applies water below the surface of the land. This method utilizes underground trenches and pipelines for the transportation of water. The pipes’ perforations let the water move out under the influence of applied pressure. As a result, the water moves upwards due to capillary tension and reaches the root zones of the crop plants. The depth of the pipes is greater than 40 centimeters (cm) in most cases. Sub-surface irrigation includes artificial waterbeds construction and works particularly well for plants with a shallow root system. It is one of the most efficient systems for soils with low water holding capacity as it reduces the water losses due to evaporation.